Coin-controlled telephone system.



O. W. MAHODL 'GOIN CONTROLLED TELEPHONE SYSTEM.

APPLICATION FILED SEPT. s. 1904.

iwlmeaaes. I 31wenm:- J charle SW Mah on 3 un/Q yaw/MC @i Home UNITEDSTATES Patented May 16, 1905.

PATENT OFFICE.

COIN-CONTROLLED TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent N 0. 789,925, dated May 16,1905.

Application filed September 6, 1904. Serial No. 223,331.

To all whom, it may concern:

Be it known that I, CHARLES W. MAHON, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook, and State ofIllinois, have invented a new and useful Improvement in Coin-ControlledTelephone Systems, of which the following is a specification.

My invention relates to that class of telephone systems in which thepayment for the service is made by the user depositing a coin or tokenin'a mechanism associated with the telephone. In some of the systemsalready in use involving this method of payment it is necessary todeposit the coin as a means of giving a signal to the operator in thecentral oifice. In this arrangement there is the objection that, becauseof some imperfection in the condition of the telephone or of the line orof the central-office apparatus, it may be impossible to display thesignal even though the coin be dropped, and thus the subscriber may makethe prepayment without receiving the service, the coin or token thenbeing beyond his recovery. In other systems it is intended that the coinshall be deposited at the request of the operator after the connectionis established. There is an objection in this method in that theattention of the operator is required after she has made the connectionand called the subscriber, so that she may collect the coin byelectrical means if the conversation occurs and may return it to thesubscriber by electrical means if no conversation results.

In many localities telephone systems having switchboards manuallyoperated are being superseded by systems equipped with automaticapparatus in which the connections between the lines are established byautomatic switches controlled and directedover the line throughelectrical means by the subscriber. As in such systems there is nosignal to be set before an operator and there is no operator to collector return the coin at the time of conversation, it is evident thatmethods adapted to the manual are not adapted to the automatic systems.

The object of my invention is to enable a subscriber whose station isequipped with mechanism operating in conjunction with automaticmechanism to connect hisline with that of a desired subscriber and tocause the calling subscriber to deposit a proper coin or token in thecoin-collector if he secures the conversation for which the charge ismade. I attain these objects by means of mechanism and circuitsillustrated in the accompanying drawings, in which Figure 1 shows thecircuits and mechanism of the telephone set, and Fig. 2 one of thepositions of an interlocking relay.

I show the essential features of my invention associated with thecircuit of a telephonesubstation set of the type adapted to be used withthe automatic telephone system of most general employment. In thissystem current impulses are sent over the line to direct and controlmechanism in the central oifice electrically associated with the line.As the sole object of these impulses and the operations they control inthe central oflice is to connect the line of the calling subscriber withthat of the desired correspondent, I do not illustrate the mechanisminthe central oflice, but show merely the means existing at thesubstation to accomplish this result.

In Fig. 1 of the drawings, 1 is a hook-switch lever. It is provided witha projection 2 so formed and so related to the spring 3 that when thehook passes upward upon the removal of the receiver from it it willcause no contact between the springs 3, 4, and 5, but when the hookmoves downward when the re ceiver is hung on it it will move the spring3 into contact with the spring 4 and that into contact with the spring5, crossing the three together. The hook-switch lever 1 also is relatedto the springs 7 to 11, inclusive, in such a way that it makes andbreaks contacts among them by its motion. When the lever is up, there iscontact between the springs 7 and 8 and between the springs 10 and 11.hen the hook is down, there is contact between the springs 8 and 9. Theset and adjustment of the springs and the existence of theinsulating-pieces l2 and 13 enable these contacts to be made and preventothers.

The springs 14 and 15, arranged to make independent contacts with thepoint 16, are those which are controlled by the signal-sending mechanismat the subscribers station, by which contacts he secures connection withthe desired line. I have omitted from the drawings elaborateillustration of the mechanical means of controlling the contacts betweenthe pieces 14 and 16 and 15 and 16. The operation of calling is merelyto make successive contacts between the spring 14 and point 16 as manyin number as there are units in the digit of the number called,following each series by one contact of the spring 15 upon the point 16.This will send first a series of im-' pulses over the line-wire 17ending with one impulse over the line-wire 18. This will be repeated foreach digit. For instance, if the number called is 2,342 there would befour series of impulses, the first one being two contacts of the spring14 with the contact 16 followed by one contact of the spring 15 with thecontact 16, then a second series of three contacts on the part of spring14 followed by one on the part of spring 15, then a series of fourcontacts on the part of the spring 14 followed by one on the part ofspring 15, and, lastly, two contacts on the part of spring 14 followedby one contact on the part of spring 15. The impulses which result fromthese contacts are caused by current from a source of energy in thecentral ofiice, and, as I here show, the conditions are with referenceto the ground. The ground connections of'the impulse-transmitting devicejust described are established by contact between the spring 19 and thepoint 20, the spring 19 being wired to the ground-wire 43. This contactis normally open, but is made as an immediate preliminary to the sendingof any impulse on the part of the subscriber. The connection between thespring 19 and the point 20 is not broken-until the receiver has beenrestored to its hook at the completion of the conversation. For the sakeof clearness I omit this element of mechanism also from the drawings, asitis in general commercial use.

Upon the completion of a series of current impulses to establish aconnection the pressure of the ringing-button 38 causes the spring 39 tobreak from the contact 40 and make with the contact 41. Under theconditions which exist this will place a ground upon the line- Wire 17,and the central-oflice mechanism being adapted for the purpose thisimpulse will cause the ringing of the bell of the desired subscriber.

In the present actual use of the automatic telephone system having thesefeatures impulses are sent over the wires of the line directly. For thepurpose of my invention I includethe winding of a relay 21 in one of theimpulse-circuits from the contact-spring 15 to the line conductor 18 inthe drawings. The relay 21 is equipped with an armature 22,

adapted when actuated to connect together the three springs 23, 24, and25. The armature is also mechanically so related to armature 26 of anelectromagnet or relay 27 that when it has moved to effect the contactmentioned it will be locked in position and prevented from falling backto break the contacts between springs 23, 24, and even though thewinding of its relay 21 is denergized. This condition is shown in Fig.2. When it is recalled that no connection can be set up between twolines without an impulse being sent over the line-wire 18, it will beseen that one of the first things to happen in setting up a connectionwill be to energize the relay 21. As this closes together the springs23, 24, and 25, these circuit relations will be established at thebeginning of each attempt at COHVGISZL.

tion and will exist throughout the connection unless the armature 22 isset free by a further action. The circuit relations established by thecontact between the springs 23, 24, and 25 are two first, by contactbetween springs 23 and 24 a low-resistance and non-inductive shunt 28 isplaced around the telephone-receiver. This is of such relation to theresistance of the telephone-receiver itself as to carry when it is inshunt with the receiverso much of the voice-current which wouldotherwise pass through the receiver as to leave received speech onlyfairly audible, but suflicient for practical purposes. While the shunt28 is of high enough resistance to enable speech to practically bereceived, it is of such low resistance that the comparatively feeblevoice-currents which can be caused by speaking into the receiver as amagneto-transmitterwill pass through it in large proportion relative towhat will pass over the line. Conversation with a distant correspondentis thus impossi- I find that.

ble by speaking into the receiver. with the ordinary commercial designof telephone-receivers the shunt 28 will bea practical one if ofaresistance of about seven ohms; second, the contact between the springs24 and 25- places a shunt of negligible resistance around the secondarywinding 29 of the induction-coil 30. As voice-currents upon the line arecaused by current variations in the primary winding 31 of theinduction-coil through the agency of the battery 32 and transmitter 33,there is no means of sending voice-currents from the transmitter overthe line, while the secondary winding 29 is thus short-circuited; butthe electromagnet or relay 27 is adapted to attract its armature 26 anddraw it out of engagement with the armature 22 when current passesthrough its winding, and current will so pass when a ground is placedupon the contact-point 34 associated with the spring 35.

The coin-chute 36, adapted to receive a coin IIC it. As the spring 35 isconnected to ground, the point 34 will be grounded at the time ofcontact, the electromagnet or relay 27 will be energized, and thearmature 26 will be drawn against the force of its retractile spring 37outot' engagement with the armature 22. The force of the springs 23, 24,and 25 will then cause them to break contact with each other and willforce the armature 22 into a position wherein it will not be relocked bythe armature 26 until its relay 21 has been renergized. The conditionsare thus again as shown in that part of Fig. 1 which illustrates thesedetails.

The dropping of a coin being thus a means under the control of thesubscriber for restoring conditions whereby he may speak to hiscorrespondent prepayment for the conversa-- tion is insured, as while hemay know that the called subscriber has responded, because he hears thatresponse in his receiver, he may speak over the line neither by the useof his transmitter nor his receiver.

Upon the completion of the conversation the hanging up of the receiverwill result in the crossing together of the springs 3, 4, and 5, sendingcurrent impulses over both wires of the line, releasing the mechanism inthe central oflice, leaving it in readiness to receive another call.

I find it of advantage for harmonious operation of the various parts ofthe system to make the winding of the relay 21 relatively low. I havefound thirty ohms to be a satisfactory and convenient resistance. Also Ifind it of advantage to have the winding of the relay 27 relativelyhigh, and I find it satisfactory to make this resistance about onethousand ohms. The relay 27 and the ringer 42 being in shunt with eachother, any currents which actuate the ringer will also actuate the relay27, thus unlocking the shunts upon the telephone set in case they shouldexist at the time of receiving a call.

I do not desire to limit myself to the particular adaptation of myinvention to the circuits of the automatic system which I have shown anddescribed, as it is evident that by minor modifications it can beadapted to other systems in which central oifice connections depend uponimpulses over the line and even to still other systems in whichconnections are set up in other ways.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

1. In a coin-controlled telephone, transmit ting-circuits, areceiving-circuit, an interlocking relay, and means whereby the1nterlocking of said relay Wlll render the tI'flI'lSIIllli'DGK- circuitsinoperative until said interlocking is released, substantially asdescribed.

2. In a coin-controlled telephone, transmitting-circuits, areceiving-circuit, interlocking relays, means whereby said relays willbe interlocked upon the making of a call, means whereby saidinterlocking will make said transmitting-circuits inoperative, and meanswhereby a deposited coin or token will release said interlocking,substantially as.described.

3. In a coin-controlled telephone, a transmitting-circuit, areceiving-circuit, a coin-receiving device, a signal receiving device,means whereby the transmitting-circuit may be rendered inoperative inthe making of a call, means whereby the transmitting-circuit may berendered operative by the deposit of a coin or token, and means wherebythe operation of the substation signal-receiving device will render thetransmitting-circuits operative, substantially as described.

4. In combination in an automatic telephone system, signal-sendingelements, a transmitceiver, will render said transmitting-telephoneoperative, substantially as described.

5. In a coin-controlled telephone, transmitting-circuits,receiving-circuits, interlocking relays, electromagnetic means forlocking one of said relays with the result of making saidtransmitting-circuits inoperative, and means for restoring saidtransmitting-circuits to operating condition by electromagneticallyunlocking said interlocking relays through the agency of the payment ofa coin or token, substantially as described.

6. In a coin-controlled telephone, a telephone receiver, a telephonetransmitter, an induction-coil, a shunt-coil, a relay adapted to placesaid shunt-coil in electrical shunt with said telephone-receiver and toshort-circuit the secondary winding of said induction-coil, anelectromagnet adapted to lock said relay, a coin-collector adapted bythe act of collecting a coin or token to release said relay from itslocked condition, substantially as described.

Signed by me at St. Louis, in the State of Missouri, in the presence oftwo witnesses.

CHARLES W. MAHON. Witnesses:

W. F. ROTH, E. E. DEWEY.

